1. Field of the Invention
The invention relates to a method for forming a membrane bioreactor, and more particularly to a method for forming a facultative-organism-adapted membrane bioreactor with facultative microbe as predominant microbe.
2. Description of the Related Art
A membrane bioreactor (MBR) is the combination of a membrane separation technology and a bio-reaction technology, and is widely used for treatment of municipal and industrial wastewaters. Membrane bioreactors exist in various forms such as submerged membrane bioreactor, separated membrane bioreactor and so on. By membrane bioreactor, the separation effect of solid and liquid in a system has been improved, and thereby the effluent quality and volume loading of a treatment system have been enhanced greatly.
However, nowadays widely-used membrane bioreactors are pure aerobic membrane bioreactors. These pure aerobic membrane bioreactors have many disadvantages. Firstly, to maintain a good scouring effect against the membrane and ensure sufficient oxygen for aerobic microbe to degrade pollutants, a high-powered blower is needed to provide oxygen for the membrane bioreactor, thereby resulting in high energy consumption. Secondly, in a pure aerobic membrane bioreactor aerobic microbe is predominant, although the aerobic microbe has a faster degradation rate on the sludge, its reproductive cycle is much shorter than that of facultative or anaerobic microbe, and thereby sludge yield in an aerobic membrane bioreactor is much more than that in a facultative or anaerobic membrane bioreactor, resulting in high sludge yield coefficient and difficulty to remove the sludge. Thirdly, under aerobic conditions, microbe can only convert ammoniacal nitrogen of wastewater into nitrate nitrogen and absorb phosphor, but cannot release phosphor; the further removal of nitrogen and release of phosphor need to be conducted in facultative or anaerobic conditions, which cannot be achieved in a pure aerobic membrane bioreactor and results in a bad efficiency of nitrogen and phosphorus removal.